1. Field of the Invention
The present invention relates to a check valve having a function of adjusting the flow rate of a fluid. More particularly, the present invention relates to a check valve which is installed at a side edge of a bag made of a plastic film and has a construction of adjusting the take-out amount of the fluid and is capable of filling the fluid into the bag and taking it out therefrom reliably and preferably.
2. Description of the Related Art
There are proposed many types of check valves for filling a fluid into a bag or a container and taking it out therefrom as necessary. For example, a check valve was devised by the present applicant and registered by the Japanese Patent Office at utility model at No. 3015272.
The registered utility model relates to an appliance (A) for filling a fluid into a sealing bag (B) and taking it out therefrom and to the sealing bag (B) provided with the appliance (A). As shown in FIG. 12, the appliance (A) comprises the guide pipe 21 which is fitted closely in the opening positioned at an edge of the flat check valve (V) consisting of a plastic film and installed at a side edge of. the sealing bag (B); and a flow pipe 22 longer than the guide pipe 21 and inserted thereinto such that it is axially movable therein. At least one guide groove 23 extending axially is formed on the inner surface of the guide pipe 21. At least one engaging step 24 is formed such that the engaging step 24 is apart from the guide groove 23. Further, a convexity 25 having a predetermined length and extending axially is formed on the outer surface of the flow pipe 22 at one side thereof. The convexity 25 is inserted into the guide groove 23. A gripping flange 26 is formed at an end of the flow pipe 22.
Unlike the conventional construction, this construction eliminates the need for performing a troublesome operation of inserting a narrow pipe such as a straw into the flat check valve (V) each time the fluid is filled into the sealing bag (B) and discharged therefrom. That is, this construction allows the fluid to be filled into the sealing bag (B) and discharged therefrom smoothly and reliably at any time and place. But the check valve V has the following problem:
That is, a member for adjusting the flow rate is not provided on the flat check valve (V) made of the plastic film or on the appliance (A) installed in the duct of the check valve (V). Thus, it is impossible to adjust the discharge amount of the fluid. Further, in order to allow the check valve (V) to perform its function, it is necessary to extend the flow pipe 22 in a long distance axially outwardly from the sealing bag (V). Therefore, it is inconvenient to carry the check valve (V) or difficult to handle it. Further, repeated axial reciprocating movement of the duct 22 causes the check valve (V) made of the thin plastic film to be damaged, thus deteriorating its function or making it impossible to perform its function.
The present inventor filed a patent application (application No. 1996-84698) with the Japanese Patent Office on Mar. 12, 1996 (published Sep. 16, 1997) to solve the above-described problem.